The present invention relates to a liquid delivery system which uses negative pressure to deliver liquid out of a liquid container, more specifically, a liquid delivery system for delivering liquid to a liquid jet recording apparatus which records images on recording medium. It also relates to a replaceable liquid container for the liquid delivery system, and a head cartridge.
There are a number of liquid delivery methods which use negative pressure to deliver liquid out of a liquid container. In the field of an ink jet recording apparatus, for example, an ink container which provides an ink jet recording head with negative pressure has been proposed, and has been put to practical use, in the form of an ink jet cartridge which integrally comprises a recording head and a negative pressure providing ink container. There are a number of ink jet cartridges, which can be classified into two groups: those which cannot be separated into a recording head and an ink container (ink storing portion), and those which can be separated into a recording means and an ink storing portion. In the case of the latter group, they can be individually separated from a recording apparatus, but remain united when they are used for recording.
There are various methods for generating negative pressure in the aforementioned liquid delivery system, and the simplest one is to use the capillary force of porous material. An ink container used for such a method comprises a shell, and a piece of porous material such as sponge for storing ink. The shell is provided with an air vent through which the atmospheric air is taken into the ink storing portion of the ink container so that ink is smoothly delivered during a printing operation. It is preferable that the porous material is compressed into the shell to fill virtually the entirety of the internal space of the ink container.
However, the usage of porous material as ink holding material creates some problems. One such problem is that the filling of an ink container with porous material reduces the ratio of the amount of ink storable in an ink container to the internal space of the ink container. In order to solve this problem, the applicants of the present invention proposed an ink container, which is disclosed in EP0580433 (official gazette). According to this proposal, an ink container is provided with a virtually sealed ink reservoir, and a negative pressure holding chamber in which a negative pressure generating member is held. The internal spaces of the ink reservoir and negative pressure generating member holding chamber are connected through a passage, and the negative pressure generating member holding chamber is open to the atmosphere. The applicants of the present invention also disclosed another invention disclosed in EP081531 (official gazette). According to this invention, an ink reservoir is made replaceable.
In the case of the aforementioned ink container, the ink within the ink reservoir is delivered from the ink reservoir to the negative pressure generating member holding chamber, as the atmospheric air displaces the ink within the ink reservoir in response to the ink delivery from the ink reservoir. Thus, the aforementioned ink reservoir has merit in that the negative pressure is kept virtually constant while the ink is delivered during this gas-liquid exchange stage.
The applicants of the present invention also proposed a liquid storing container, which is disclosed in EP0738605 (official gazette). According to this proposal, a liquid storing container comprises an outer shell in the form of a virtually polygonal prism, and a liquid storing portion placed in the outer shell. This proposal is characterized in that the liquid storing portion is similar in shape to the outer shell, the outward surface of each of its walls being in contact with, or closely following, the inward surface of the correspondent wall of the outer shell; that the liquid storing portion is enabled to deform in response to the outward delivery of the liquid stored in the liquid storing portion; and that the thickness of the walls of the liquid storing portion is greater at its corner portions than at the center portions of the walls. The liquid storing portion of this liquid storing container contracts by a proper amount in response to the ink delivery therefrom (liquid in the ink storing portion is not displaced by gas), so that liquid can be delivered while maintaining a proper amount of negative pressure. Therefore, unlike a conventional ink storing member, which is in the form of a pouch, this liquid storing container does not have any restriction regarding its positioning. Thus, it can be mounted on a carriage. Further, ink is directly stored in the storing portion, which makes this invention superior also in terms of ink storage efficiency.
It should be noted here that, in the case of an ink container of such a type that comprises a negative pressure generating member holding chamber such as the one described above, and a matching ink reservoir which is placed adjacent to the negative pressure generating member holding chamber, and is provided with a predetermined amount of storage space, gas is introduced into the ink reservoir to displace the ink (gas-liquid exchange occurs) as the ink within the ink reservoir is delivered into the negative pressure generating member holding chamber.
In other words, as the ink in the ink reservoir is delivered to the negative pressure generating member holding chamber, the atmospheric air is introduced into the ink reservoir in response to the ink delivery, by an amount equal to the amount of the delivered ink. Therefore, the ink reservoir is occupied with both the introduced outside air, and ink. If the air in the ink reservoir is expanded by the changes (for example, daily temperature fluctuation) in the ambience in which the printer is used, the ink within the ink reservoir is sometimes forced into the negative pressure generating member holding chamber side by the expansion. For this reason, in the past, the ratio of the amount by which the ink is moved, to the air expansion, in various environments in which the recording apparatus is used, had to be taken into consideration to provide the negative pressure generating member with the maximum amount of buffering space, in terms of practical use. As a result, it was very difficult to provide an ink reservoir with an internal volume greater than a certain size.
In order to solve the above described problems, the inventors of the present invention analyzed in detail an ink container of such a type that comprised a negative pressure generating member holding chamber, and an ink reservoir matching the negative pressure generating member holding chamber, in the state in which the ink reservoir contained air. As a result, it was discovered that the delivery of the ink in the ink reservoir to the negative pressure generating member holding chamber is directly linked to the introduction of the outside air, and therefore, in order to solve the above described problem, the amount by which ink moves from the ink reservoir to the negative pressure generating member should be regulated.
Further analysis led the inventors to an idea that, although it is impossible to prevent the air present in the ink reservoir from expanding, it is possible to contain the effect of the expansion of the air in the ink reservoir, within the ink reservoir, which is contrary to the conventional concept.
The present invention was made as the result of further study of the aforementioned discovery and knowledge carried out by the inventors of the present invention.
An essential thought kept in the minds of the inventors of the present invention was in order to reliably deliver ink even immediately after the exchange of the ink reservoir, a structure for enhancing the introduction of atmospheric air, which effectively functions without being clogged by the adhesion of solidified ink or the like, should be provided.
The primary object of the present invention is to provide a liquid delivery system superior in terms of practicality, that is, a liquid delivery system, the ink reservoir (liquid storing container) of which is exchangeable, and is capable of reliably delivering ink while generating and maintaining a stable amount of negative pressure, and also to provide a liquid storing container usable in such a liquid delivery system.
Another object of the present invention is to provide various inventions related to a head cartridge or the like with which the aforementioned liquid delivery system is usable.
The specific means in the present invention for accomplishing the above described objects will be become apparent from the understanding of the structures described below.
According to a characteristic aspect of the present invention, the liquid delivery system comprises: a negative pressure generating member holding chamber, which is provided with a liquid delivery portion for outward ink delivery, and an air vent portion, and stores therein a negative pressure generating member for retaining liquid therein; and a liquid storing container, which is exchangeably connectable to the negative pressure generating member holding chamber, and forms a virtually sealed space except for the joint portion by which it is connected to the negative pressure generating member holding chamber, wherein the liquid storing container to be connected to the negative pressure generating member holding container is provided with an atmospheric air introduction groove which is for displacing the liquid delivered from the liquid storing container, with the gas, by introducing gas into the liquid reservoir, and which is located at the joint portion of the ink reservoir, by which the ink reservoir is connected to the negative pressure generating member holding container.
According to another characteristic aspect of the present invention, a liquid storing container, which is exchangeably connectable to a negative pressure generating member holding chamber which is provided with a liquid delivery portion for outward ink delivery and an air vent portion, and stores therein a negative pressure generating member for retaining liquid therein, forms a virtually sealed space except for the joint portion by which it is connected to the negative pressure generating member holding chamber, and stores liquid, is provided with an atmospheric air introduction groove which is for displacing the liquid delivered from the liquid storing container, with the gas, by introducing gas into the liquid reservoir, and which is located at the joint portion of the ink reservoir, by which the ink reservoir is connected to the negative pressure generating member holding container.
According to the above described liquid delivery system and liquid storing container, the atmospheric air introduction groove is replaced as the liquid reservoir is replaced. Therefore, the atmospheric air introduction groove does not malfunction, making it possible to provide a liquid delivery system capable of reliably delivering ink. Further, a portion of the liquid in the liquid storing portion can be moved into the negative pressure generating member storing container with the use of the capillary force of the negative pressure generating member at the time of the connection. Therefore, it is assured that the liquid within the liquid storing container is reliably delivered for usage, regardless of the state of liquid retention in the negative pressure generating member, at the joint portion, upon installation.
Further, according to another characteristic aspect of the prevent invention regarding the above described liquid delivery system and liquid storing container, the liquid storing container comprises a liquid storing portion which stores liquid and is capable of generating negative pressure by deforming in response to the liquid delivery therefrom, a shell for covering the liquid storing portion, and an air vent through which atmospheric air can be introduced between the shell and the liquid storing portion.
In the case of a structure comprising a liquid storing portion such as the one described above, the liquid storing portion is elastically deformable. Therefore, even if the air or the like introduced into the liquid storing portion expands in response to ambient changes, the effect of the expansion is cushioned by the elasticity of the liquid storing portion, which works in the direction to restore the liquid storing portion to the original shape.
The liquid delivery port of the liquid storing portion is desired to be sealed with a sealing member. This sealing member is desired to separate from the liquid delivery port after the connection of the liquid storing container to the negative pressure generating member holding container. The negative pressure generating member holding container holds the negative pressure generating member between the aforementioned atmospheric air introduction groove and air vent.
It is possible to provide the negative pressure generating member holding container with a groove which becomes integrated with the aforementioned atmospheric air introduction groove to allow gas-liquid exchange.
Further, according to another characteristic aspect of the present invention, a head cartridge is provided with a recording head portion which records images by ejecting the liquid delivered from the aforementioned negative pressure generating member holding container.
These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.